AISI Type S1 Tool Steel

AISI Type S1 Tool Steel, quenched 955°C (1750°F), tempered 150°C (300°F) Product Information -:- For detailed product information, please contact sales. -: AISI Type S1 Tool Steel, quenched 955°C (1750°F), tempered 150°C (300°F) Synonyms -:- For detailed product information, please contact sales. -:

AISI Type S1 Tool Steel, quenched 955°C (1750°F), tempered 150°C (300°F) Product Information -:- For detailed product information, please contact sales. -: # **Product Introduction: AISI Type S1 Shock-Resisting Tool Steel (UNS T41901)** ## **Overview** **AISI S1 (UNS T41901)** is a **tungsten-chromium, silicon-alloyed, air-hardening shock-resisting tool steel**. It is specifically engineered to deliver an exceptional combination of **high toughness and good wear resistance**, making it the premier choice for applications involving severe impact and shock loading. The specified heat treatment (quenched from 955°C, tempered at 150°C) is designed to produce **very high hardness** while retaining as much toughness as possible, ideal for tools that must maintain a sharp edge under punishing conditions. ## **1. Chemical Composition (Nominal %)** S1's composition is uniquely balanced for shock resistance through silicon and tungsten. | Element | Content (%) | Primary Function | |---------|------------|------------------| | **Carbon (C)** | 0.40 - 0.55 | Provides a balance of hardness and toughness; sufficient for edge retention without excessive brittleness. | | **Tungsten (W)** | 1.50 - 3.00 | **Key element.** Forms hard, wear-resistant carbides and contributes to hot hardness and deep hardening. | | **Chromium (Cr)** | 1.00 - 1.80 | Enhances hardenability, wear resistance, and provides mild corrosion resistance. | | **Silicon (Si)** | 0.90 - 1.20 | **Critical element.** Strongly increases toughness and shock resistance by strengthening the ferrite matrix. Also improves high-temperature strength and decarburization resistance. | | **Vanadium (V)** | ≤ 0.15 | May be present in trace amounts for grain refinement. | | **Manganese (Mn)** | 0.10 - 0.40 | Aids in hardenability and acts as a deoxidizer. | | **Molybdenum (Mo)** | ≤ 0.50 | May be present to enhance hardenability and toughness. | | **Iron (Fe)** | Balance | Base metal. | **Key Chemistry Note:** The **high silicon content** is the defining feature of S1, distinguishing it from other shock steels like S5 (Mn-Si) and S7 (Cr-Mo). Silicon does not form carbides but dissolves in the ferrite matrix, dramatically increasing its strength and resilience to impact. The **tungsten provides wear resistance and hot hardness**, creating a unique synergy where the steel can withstand both heavy pounding and abrasive wear. ## **2. Physical & Mechanical Properties** *Properties after quenching from 955°C (1750°F) and tempering at 150°C (300°F).* | Property | Typical Value / Condition | |----------|--------------------------| | **Density** | ~7.80 g/cm³ (0.282 lb/in³) | | **Melting Point** | ~1510°C (2750°F) | | **Thermal Conductivity** | ~40 W/m·K (Moderate) | | **Coefficient of Thermal Expansion** | ~12.0 × 10⁻⁶/K (20-100°C) | | **Modulus of Elasticity** | 210 GPa (30.5 × 10⁶ psi) | | **Annealed Hardness** | 192-229 HB | | **As-Quenched Hardness (Air)** | ~58-60 HRC | | **Hardness (Tempered @ 150°C)** | **57-59 HRC** (Retains very high hardness) | | **Tensile Strength** | ~2000-2100 MPa (290-305 ksi) | | **Yield Strength (0.2%)** | ~1650-1750 MPa (240-254 ksi) | | **Impact Toughness (Charpy V-Notch)** | **Excellent.** Among the highest of all tool steels at this hardness level. Can be 40-60 J (30-44 ft-lbf) or higher. | | **Wear Resistance** | **Good.** Superior to other shock steels (S5, S7) due to tungsten carbides. | | **Hot Hardness / Red Hardness** | **Good.** Maintains hardness at moderately elevated temperatures better than carbon or low-alloy steels. | | **Machinability (Annealed)** | Fair (approx. 50% of 1% carbon steel). | | **Grindability** | Fair. | ## **3. International Standards & Cross-References** S1 is a well-established grade with clear international equivalents. | Standard | Designation | |----------|------------| | **UNS** | T41901 | | **AISI/ASTM (USA)** | S1 (ASTM A681) | | **ISO (International)** | **60WCrV8-2** (ISO 4957: Tool steels) – Closest match. | | **DIN (Germany)** | **1.2542** | | **BS (UK)** | **BS1** | | **JIS (Japan)** | **SKS41** | | **GB (China)** | **5CrW2Si** (A very close equivalent) | | **Common Name** | **Tungsten Silicon Shock Steel** | ## **4. Product Applications** S1 is specified for tools that must **withstand extreme impact without chipping or breaking**, while still maintaining a functional cutting edge. **Primary Applications (Hardened to ~58 HRC):** * **Chisels and Punches:** * **Cold chisels**, **masonry chisels**, and **rock drill bits**. * **Heavy-duty punches** for sheet metal and forging. * **Shearing and Cutting Tools:** * **Shear blades** for hot or cold cutting of bars, rods, and billets. * **Bolt croppers** and **circular cutters**. * **Forming Tools:** * **Hot forming dies** and **swaging dies**. * **Knives for hot cutting** of metals. * **Other Impact Tools:** * **Driver bits** for impact wrenches. * **Jacks hammer bits**. * **Blacksmith tools** (hot sets, fuller tools). **Why this specific heat treatment?** * **Quenching at 955°C (1750°F):** This is a typical austenitizing temperature for S1. It ensures dissolution of sufficient carbon and alloying elements to achieve full hardness upon air cooling. **Air hardening** minimizes distortion and quench cracking risk compared to oil or water quenching. * **Tempering at 150°C (300°F):** This is a **very low tempering temperature**, chosen to **retain maximum hardness (57-59 HRC)** while providing a minimal amount of stress relief. Tools tempered at this temperature are designed for **maximum wear resistance and edge retention under impact**, accepting a slightly lower toughness level than if tempered at a higher temperature (e.g., 425°C for S1 would yield ~50 HRC but much higher toughness). This regimen is for the most severe abrasive/impact applications. ## **5. Specified Heat Treatment Process** 1. **Preheating:** Essential. Preheat slowly to **650-700°C (1200-1290°F)** to minimize thermal stress, especially for complex shapes. 2. **Austenitizing:** * Heat to **950-960°C (1740-1760°F)**. The 955°C target is ideal. * Soak for **30-45 minutes per inch** of cross-section after the entire part reaches temperature. 3. **Quenching:** **Quench in still or forced air.** Oil quenching is possible for maximum hardness in thin sections but increases distortion risk. Air cooling is standard and sufficient due to high hardenability. 4. **Tempering:** * **Temper immediately** after the part reaches room temperature (50-70°C). * Heat to **150°C (300°F)** and hold for **1-2 hours per inch** of thickness. * **Double tempering is strongly recommended** to ensure complete stress relief and stabilization. Cool in air after each temper. ## **6. Comparative Advantage** | Property | S1 vs. Other Shock Steels | |----------|---------------------------| | **Toughness** | Very High, but typically slightly lower than **S7** at the same hardness due to S7's simpler microstructure. However, S1's toughness at high hardness is exceptional. | | **Wear Resistance** | **Best among S-series** due to tungsten carbides. Superior to S5 and S7. | | **Hot Hardness** | **Best among S-series** due to tungsten. | | **Application Focus** | **Heavy impact + abrasion.** Where S7 is for pure impact (chipping hammers) and S5 for heavy shearing, S1 is for tools like hot cuts, chisels, and shear blades that see both forces. | --- **Disclaimer:** The specified tempering at 150°C results in very high hardness but lower toughness compared to tempering at higher temperatures. This treatment is suitable for applications where extreme edge retention is needed under impact, but not for tools subject to extreme, unguided bending forces. For maximum toughness, tempering at 425-540°C is standard, yielding 45-52 HRC. Always consult material data sheets and consider the specific mode of failure in the application. The air-hardening nature of S1 makes it more dimensionally stable than oil-hardening grades but proper preheating is critical to prevent cracking. -:- For detailed product information, please contact sales. -: AISI Type S1 Tool Steel, quenched 955°C (1750°F), tempered 150°C (300°F) Specification Dimensions Size： Diameter 20-1000 mm Length <6753 mm Size:We can customized as required Standard： Per your request or drawing We can customized as required Properties（Theoretical） Chemical Composition -:- For detailed product information, please contact sales. -: AISI Type S1 Tool Steel, quenched 955°C (1750°F), tempered 150°C (300°F) Properties -:- For detailed product information, please contact sales. -:

Applications of AISI Type S1 Tool Steel, quenched 955°C (1750°F), tempered 150°C (300°F) -:- For detailed product information, please contact sales. -: Chemical Identifiers AISI Type S1 Tool Steel, quenched 955°C (1750°F), tempered 150°C (300°F) -:- For detailed product information, please contact sales. -:

Packing of AISI Type S1 Tool Steel, quenched 955°C (1750°F), tempered 150°C (300°F) -:- For detailed product information, please contact sales. -: Standard Packing: -:- For detailed product information, please contact sales. -: Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and steel drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 3224 gallon liquid totes Special package is available on request. E FORUs’ is carefully handled to minimize damage during storage and transportation and to preserve the quality of our products in their original condition